Probiotics are believed to have benefits for digestive health, especially when the microbiome in the gut has been disrupted due to illness or treatment with antibiotics, although evidence to support the many claims that probiotics can improve the diversity of gut bacteria – or health in general – is scant.
The benefits of probiotics are being investigated and some evidence has emerged to suggest probiotics may have benefits for respiratory health and could help to alleviate the symptoms of upper respiratory infections (URIs) such as the common cold and flu and even prevent contraction of the diseases.
A human prospective trial was conducted at the Beijing Chaoyang Hospital on 134 volunteers aged between 25 and 45, all of whom had contracted influenza or the common cold at least four times in the past 12 months.
In the single center, randomized, double-blind, prospective trial, half of the study participants were provided with a probiotic yoghurt drink which was consumed after lunch for 12 weeks. The other half received a placebo yoghurt drink. The probiotics were provided in lyophilized powder form from Chr. Hansen in Denmark and were given to the probiotic group in 125ml of yoghurt. The probiotics contained three strains of Lactobacillus – L. paracasei, L. casei 431, and L. fermentium PCC.
Analysis of the results of the study showed a statistically significant difference between the incidence of URIs between the groups.
4.5% of the group on probiotics exhibited flu-like symptoms and at least one URI symptom compared to 16.4% of the placebo group. 37.3% of the placebo group had at least one URI symptom but no fever, compared to 19.4% of the probiotic group.
The researchers concluded that consuming the probiotics on a daily basis had a positive effect on the immune system resulting in an improved response to the common cold and influenza and that taking probiotics reduced the incidence of URIs.
Consumption of the probiotics appeared safe, although one member of the trial experienced diarrhea which was attributed to the use of probiotics and was removed from the trial.
While the findings of the study are positive, the researchers did note that further in vivo studies and a larger sample size would be required to confirm the findings and to determine whether consumption of probiotics prolongs resistance to infections and diseases in humans.
The study is detailed in the paper – Prospective study of probiotic supplementation results in immune stimulation and improvement of upper respiratory infection rate – which was published in the journal Synthetic and Systems Biology, on March 12, 2018. DOI: 10.1016/j.synbio.2018.03.001